Product Page - Custom Form Scroll

Hi all,

My website has a product where we require the customer to fill out a custom form in order to complete the purchase. For some reason, the form I created will not scroll down when opened. 

https://www.sdfsa.org/store/resource-organizing-workshop

Click on 'register'

If you place your cursor in any of the visible fields within the form, you can move through the fields/questions by hitting 'tab'

Is it due to the code I've added into the code injection and CSS areas?

Or is there code that I can add to my website to ensure that this form scrolls down? Or code that can open the form in a new page rather than a lightbox?

Please help, I really need this to work. Thank you.

@Ziggy, you have saved my life! I was at my wit's end and pulling my hair out for days over this. Thank you! Checking out your website now, as there are other things I'd love to fix on our squarespace site and I am looking for a consultant to help. I'll have to get in touch with you soon!